System for establishing and maintaining a clock reference indicating one-way latency in a data network
A method for indicating one-way latency in a data network, with continuous clock synchronization, between first and second node having clocks that are not synchronized with each other includes a continuous synchronisation session and a measurement session. The method repetitively sends predetermined synchronization messages from the first node to the second node and from the second node to the first node, calculates a round trip time for each message at the first node, updates a synchronization point if the calculated round trip time is smaller than a previously calculated round trip time, stores the updated synchronization points of a synchronization window, and calculates a virtual clock from the updated synchronization points of the synchronization window. The measurement session collects multiple measurements of one-way latency between the first and second nodes using the virtual clock, and generates a latency profile by interpolating the multiple measurements.
1. A system for adapting to clock offsets between a responding node and one or more requesting nodes in a network, the system comprising:
one of said responding nodes coupled to the requesting node via the network, the responding node maintaining a virtual clock associated with each of said requesting nodes and transmitting a synchronization requests to each of said requesting nodes;
wherein, in response to a number of synchronization requests, the requesting node transmits a synchronization response to the responding node; and
wherein responding node calculates a round-trip delay measurement based on the synchronization response and produces a latency profile for the requesting node.
2. The system of claim 1 wherein the responding node further comprises a synchronization point associated with the requesting node, the synchronization point produced based on the round trip delay measurements.
3. The system of claim 2 wherein the synchronization point is periodically updated using an additional round trip delay measurement.
4. The system of claim 1 wherein said number of synchronization requests is predetermined.
5. The system of claim 2 wherein the synchronization point is produced by calculating a sum of least-squared method.
6. A method for adapting to clock offsets between a responding node coupled to one or more requesting nodes via a network, the method comprising:
maintaining by the responding node a virtual clock associated with each of said requesting nodes and transmitting a synchronization requests to each of said requesting nodes;
transmitting by the requesting node, in response to a number of synchronization requests, a synchronization response to the responding node; and
calculating at the responding node a round-trip delay measurement based on the synchronization response and producing a latency profile for the requesting node.
7. The method of claim 6 further comprising producing a synchronization point associated with the requesting node based on the round-trip delay measurements.
8. The method of claim 7 further comprising updating the synchronization point using an additional round trip delay measurement.
9. The method of claim 6 wherein said number of synchronization requests is predetermined.